ci: install toolchain in Alpine runner

tests/test_addon_metadata.py

@@ -173,6 +173,34 @@ def test_ci_builds_and_loads_only_the_amd64_test_image() -> None:
         assert publication_primitive not in workflow
 
 
+def test_ci_installs_toolchain_without_hosted_toolcache_actions() -> None:
+    workflow = (ROOT / ".gitea/workflows/ci.yml").read_text(encoding="utf-8")
+    parsed = yaml.safe_load(workflow)
+    steps = parsed["jobs"]["validate"]["steps"]
+    setup_command = next(
+        step["run"] for step in steps if step.get("name") == "Install test toolchain"
+    )
+
+    assert "actions/setup-python" not in workflow
+    assert "actions/setup-go" not in workflow
+    for required_command in (
+        "apk add --no-cache curl python3 py3-pip",
+        "go1.27.1.linux-amd64.tar.gz",
+        "63d339f0da5ab53635a56f2490a7984dfe12dfcff22ad749f63edaf590168445",
+        "sha256sum -c -",
+        "python3 -m venv .venv",
+        ".venv/bin/pip install --requirement requirements-dev.txt",
+    ):
+        assert required_command in setup_command
+
+    validation_command = next(
+        step["run"]
+        for step in steps
+        if step.get("name") == "Validate metadata, patches, and process manager"
+    )
+    assert validation_command == ".venv/bin/pytest -q"
+
+
 def test_patch_payloads_disable_git_whitespace_errors() -> None:
     result = subprocess.run(
         [